[yamahaSHO]

About a month or so ago, I picked up a Blouch 20g (TD05H/8cm) as I was craving a little more power. I love the spool and torque of the stock turbo, but it seems to die off too quickly for my tastes. I generally find myself shifting at 6,000 RPM because of this.

I have been looking to buy injectors soon and was thinking I'd go large enough to run E85 after finding quite a few stations in my area that carry it. One of the biggest problems I am fighting is trying to get the best bang for the buck without sacraficing quality (I've modified to the point of deminishing returns on another car), and that I'm working with the side-feed configuration. I have pretty much decided on DW injectors and was originally looking at 850cc injectors. From much of the research I've done, 850cc may handicap me in not only power, but safety. I have been e-mailing back and forth with DW to find out that they have some side-feed 1,000cc injectors in testing and this seems like it might be my best route.

With that said, I have also be reading up on the fuel system on these cars and it is the most mixed information I've read on just about anything. Many say that the stock rails are good for quite a bit of power (on gas), others say that fuel delivery is not equal to all injectors. With the #4 pistons on these cars taking a crap, it appears to me that it is the configuration of the fuel system with that injector being the last to see a pressure change (dealt with similar issues on the SHO's and added a dual feed setup) and could *possibly* be the culprit to these failures.

I'd really like to clarify some things to myself:

-850cc injectors are borderline for a 20g and E85
-1,000cc injectors would suffice

Does this seem like sound advice?

The other is, with the added fuel delivery need for E85 and such large injectors, should I attempt this on stock rails (and regulator), or should I install aftermarket rails (stock regulator)? The other option I have been looking at are the APS rails. If this were straigh gas, I wouldn't worry for the power levels I am looking at, but not having messed with E85, all I know is that it will require more fuel to get the job done, leading me into building up a bigger, better fuel deliver system.

Not that I haven't forgotten, since I didn't mention it, I am looking to get the Walbro 255 high-pressure pump. The plan will eventually be to port out the stock mainfolds and thermal coat them, add and up-pipe (when I do the turbo) and have the DP thermal coated as well. I am also looking into a Process West TMIC.

Does my thought process seem valid? Anything I may be overlooking or thinking too much about? I'm not a n00b in tuning cars, but I'm not well versed in with this STi yet and would much rather learn from others expriences first.

[07StiLtd]

You're thinking of all the right things, and it looks like you're on the right track.

Regarding the fuel rails, I'm not sure your setup and HP goals will require an aftermarket or larger fuel rail. Though #4 cylinders are more common when it comes to ring land failures, the fuel rail doesn't seem to be the definitive cause among the community. Someone please chime in if you have any confirmed data to support the theory though.

850cc's should be enough to push out 350-370hp on a 20g at 22psi. I'm around those numbers with a similar setup on my STi and still have a little wiggle room with my injectors. If you plan on going above those numbers, get the 1000cc's just to be safe

Save your money on the up-pipe get headers if you can. The STi up-pipe really isn't too bad unless you plan on bolting on a huge turbo.

I recommend:

850cc Injectors (maybe modify the stock ones for now and get them flow tested?)
Downpipe / full exhaust
255 walboro
20G
Larger Top mount or FMIC (I use a txs top mount)
k&n drop-in filter or cobb short ram filter
E85 Tuned by AWDTuning.com



Also help us out... What year is your car? Stock engine? How many miles? Any current mods? Have you done a compression test lately to test the condition of your engine as it is?

My 07 didn't last very long before #4 went, so stay cautious and plan on building an engine soon just in case!

[yamahaSHO]

Sorry, I was so busy trying to be clear/descriptive, I didn't even give my vehicle info. The car is a 2005 w/ 28k miles and the engine is healthy. Current mods are COBB TBE and APv2 w/ OTS stage II. I'm not looking to get headers. I would prefer to keep the stock cast manifolds and port/coat them (and reinstall the heat shields). I don't want to bother with hot, cracking headers.

I will be doing the tuning myself. I can't give a real whp figure as I'm going for a definite gain with safety. In addition to they different readings dyno's will give, it makes it hard. If it were like tuning my SHO and it were on a DynoJet, I'd be shotting for 350-360whp (never used a Mustang dyno).

I wonder the flow difference on the top-feed and side-feed rails. Even when tuned, the 07+ (top-feeds) seem to let go sooner. Something is causing knock in that cylinder.

[htowns_finest]

im running 860cc injectors on a green hta no problem maxed them out at 17 psi but im sure with a 20g you should more than fine with 850s

as far as rails you should be fine, im running the stock ones fine

and what do you mean safety and handicap on power

[yamahaSHO]

Originally Posted by htowns_finest

im running 860cc injectors on a green hta no problem maxed them out at 17 psi but im sure with a 20g you should more than fine with 850s

as far as rails you should be fine, im running the stock ones fine

On E85? I don't want to max out near 17 PSI (maybe a few PSI higher as the max boost would probably be at a lower RPM).

Originally Posted by htowns_finest

and what do you mean safety and handicap on power

I don't want to be injector limited to a point where I have to worry about running out of fuel (safety) before attaining the power levels I'd like.

[BAD STI]

Have you considered meth injection? Im doing a TD06H 20g with meth.

[yamahaSHO]

Absolutely no meth. I already do it on another one of my cars and if it weren't for space constraints, I'd MUCH rather run huge intercooler.

[FORCFED]

1000cc injectors - should also leave room for E85 and a larger turbo, if you ever go bigger!
Perrin or APS rails
and a walbro

[1BA06STI]

I'm on the stock turbo now with 850 sidefeeds and am only using 60-70% of my injectors on e85. I have a friend on the other hand who has completely maxed out his 850's on the td06 20g with e85. You may be able to pull it off with the 850's but don't be surprised if they limit you like his have. When I move to a bigger turbo I will be converting to topfeed since its tough to find side feed injectors that are over 1000.

[HolyCrapItsFast]

I have a 20G and 850's. Duty cycle is 85% at 23PSI wot on E85.

With a 20G you will be fine with 850's. My car won't idle well with 1000cc injectors.